Refining plate for high consistency pulp



Oct 21, 9 R. E. SHOOK, JR. ETAL 3,473,745

REFINING PLATE FOR HIGH CONSISTENCY PULP Filed Jan. 11, 1967 3 Sheets-Sheet 1 Oct. 21, 1969 R. E. sHooK. JR, ETAL 3,473,745

REFINING PL ATE FOR HIGH CONSI STENCY PULP Filed Jan. 11, 1967 3 Sheets-Sheet 5 United States Patent 3,473,745 REFINING EiLATE F012 HIGH CONSISTENCY PULP Raymond E. Shook, .lr., and Harold M. Soars, Jr., Muncy, Pa, assignors to Sprout, Waidron & Company, Inc.,

Muncy, Pa, a corporation of Pennsyivania Filed Jan. 11, 1967, Ser. No. 693,693 lint. Cl. 1392c 1/10, 7/00, 13/28 US. Cl. 241-298 7 Claims ABSTRACT OF THE DISCLOSURE It is generally recognized that a superior quality paper pulp can be produced by the refining of raw or chemically treated wood chips having a relatively low water content, known as high consistency refining. The refining of high consistency stock in disc-type refiners using conventional refining plates has been less than satisfactory for a number of reasons. One difficulty has been the formation of steam in the refiner due to the decreased amount of cooling water available in the stock. The uneven escape of steam between the rotating refiner plates is apt to cause a surge of material across the plates and a resultant uneven refining of the stock.

A further difiiculty is the tendency of conventional refiner plate configurations to cut or tear the wood fibers, thereby decreasing the strength and quality of the pul Additional problems have been encountered in maintaining a uniform feeding of the stock particularly into the outer regions of the plates. An uneven flow of stock through this region is a primary cause of pulp non-uniformity. It is essential for quality high consistency refining that a uniform stock flow be maintained across the refining plates and particularly the outer refining zone thereof.

In view of the above it can be understood to be a first object of the present invention to provide a refiner plate configuration for use in disc-type refiners which is particularly designed for the refining of high consistency raw or chemically treated wood chips to produce a pulp of significantly improved uniformity and strength.

A further object of the invention is to provide a refiner plate configuration as described which produces a gradual reduction or fibrillation of the wood fibers without the excessive production of fines or broken fibers.

An additional object of the present invention is to provide a refiner plate configuration as described which achieves a superior pulp quality by effecting a rubbing of the wood fibers against one another.

Still another object of the invention is to provide a refiner plate configuration as described which provides a controlled escape of the steam generated in the high consistency refining.

A still further object of the invention is to provide a refiner plate configuration as described which insures a uniform feeding of the stock, particularly across the outer fine-toothed zone of the plates.

To achieve the above objects, the present invention comprises a novel refiner plate attrition surface configuration which includes a plurality of radially adjoining refining zones having teeth or other attrition elements of 'ice progressively decreasing size, the outer most zone preferably comprising exceptionaly fine paralel teeth and having a non-arcuate juncture with the interiorly adjacent zone. The teeth or attrition surfaces of the several refining zones are sloped to provide a gradually decreasing spacing between the opposed plates of the refiner discs from the inner to the outer refining zones.

Additional objects and advantages of the invention will be more readily apparent from the following detailed description of an embodiment thereof when taken together with the accompanying drawings in which:

FIG. 1 is a view showing an array of refiner plates of the type embodying the present invention as they would be arranged upon a disc of a disc-type refiner;

FIG. 2 is a greatly enlarged view of the attrition surface of one of the segmental plates of the array shown in FIG. 1 showing the details of the various toothed zones thereof;

FIG. 3 is a sectional View taken along line 33 of FIG. 2 showing in particular the slope of the several refining zones;

FIG. 4 is a sectional view taken along line 44 of FIG. 2 showing a cross section of the extremely finetoothed outer refining Zone;

FIG. 5 is a view taken along line 5-5 of FIG. 2 showing the teeth of the intermediate refining zone in section;

FIG. 6 is a sectional view taken along line 66 of FIG 2 showing the large teeth of the breaker zone in sectlon;

FIG. 7 is a photomicrograph showing a typical wood pulp structure following high consistency defining with refining plates according to the present invention; and

FIG. 8 shows a photomicrograph of the same magnification showing the appearance of the high consistency stock following defining with a refining plate of conven tional configuration.

Referring to the drawings and particularly FIG. 1 thereof, a plurality of segmental refining plates 10, only one of which is shown in detail, are schematically illustrated in the ring-shaped array 11 in which they would be mounted upon one of the opposed discs of a disc-type refiner. Each segmental plate is defined by side edges 12 aligned with a radius of the ring-shaped array 11, and inner and outer arcuate edges 14 and 16. The plates in the present instance are so dimensioned that a set of 12 plates completes the array as shown in FIG. 1, each plate comprising a 30 segment of the ring-shaped array. As shown more clearly in FIGS. 2 and 3, countersunk bolt holes 18 are provided in each plate to permit demountable installation of the plates on the refiner discs.

As shown in FIG. 3, the back face 20 of each plate is accurately ground to a flat surface for mounting on a refiner disc, while the working face of the plate comprises an attrition surface 22 which, in the preferred embodiment, has a toothed configuration. As shown most clearly in FIG. 2, the attrition surface is divided into three refining zones, a breaker zone 24 adjacent the inner edge 14- of the plate, an intermediate zone 26 extending outwardly from the breaker zone, and a fine zone 28 between the intermediate zone and the outer edge 16 of the plate.

The breaker zone 24 includes relatively large, widely spaced, radially arranged breaker teeth 30 which may be of varying length and which desirably are tapered as illustrated to decrease outwardly in width, permitting the inclusion of smaller teeth 32 along the outer periphery of the breaker zone. The breaker zone, as the name implies, serves primarily to break up the larger wood chips in the stock and to feed the pulp uniformly into the intermediate zone.

The intermediate zone 26 comprises a plurality of teeth 34 which are substantially finer than the teeth of the breaker zone and which are preferably arranged in the parallel section manner illustrated in FIG. 2. The intermediate zone of each plate is divided into two sections 35 and the teeth within each section are parallel with one another, the central teeth of each section being radially aligned. A transition region 36 between the two sections as well as between sections of adjoining plates interrupts the continuity of the tooth pattern, several of the teeth being joined at their lower ends to form V-shaped tooth configurations. Rows of dams 38 are provided between the teeth of the intermediate zone to control the stock flow across the zone as will be described hereinafter.

The fine zone 28, the tooth size and juncture with the intermediate zone of which are of primary importance, comprises a plurality of very fine teeth 40 which, in the manner of the teeth in the intermediate zone, are arranged in parallel relation, there again being a division of the zone in each plate into two sections 41 corresponding to the sections of the intermediate zone. A transition region 42 of interrupted teeth between adjoining fine zone sections accommodates the interfering tooth angles.

The juncture 44 of the fine zone 28 with the intermediate zone 26 is non-arcuate in shape to provide a uniform fiow of stock across the fine zone 28 in a manner to be presently described. It will be noted that while the juncture 46 between the intermediate zone and the breaker zone is of an arcuate shape in the plate shown in FIG. 2 and thus provides a circular intersection between the two zones in the array of FIG. 1, the juncture 44 between the fine zone and the intermediate zone is of a non-arcuate configuration, each fine zone section 41 bounding the adjacent intermediate zone section 35 along a straight line 48. The juncture 44 thus comprises in each plate as illustrated in FIG. 2, two equal length angularly intersecting lines, and in the plate array shown in FIG. 1 comprises 24 equal connected chords of an imaginary circle concentric with the annular plate array. The significance of the non-arcuate zone juncture 44 is set forth below in the description of the plate operation.

As shown in FIG. 3, the toothed surfaces of all three zones of the refining plate slope inwardly to provide a substantially greater spacing of the teeth of the breaker zone than those of the fine zone when the plates are mounted in opposed relation in a disc refiner. The teeth of the breaker zone are inclined at a substantially greater angle than those of the intermediate and fine zones which are preferably inclined at the same slope angle a as illustrated in the drawings. This slope of the refiner plate teeth serves an important function in feeding the stock smoothly across the refining zones and in conjunction with the fine toothed zone 28 and the non-arcuate juncture 44 of the intermediate and fine zones is essential to the production of superior quality pulp. The optimum slope of the several plate zones is dependent upon the intended speed of operation of the plate, a slower operating speed requiring a greater tooth slope as a general rule.

For refining operation, the plates are mounted on the opposed faces of the refiner discs to form a ring-shaped array on each disc face. One or both of the opposing refiner discs are rotated to provide relative rotation of the spaced plate arrays. The stock to be refined, which may for example be raw or chemically treated wood chips, is introduced at the center of the discs under pressure, the stock moving radially between the plate attrition surfaces under centrifugal force. As the stock moves across the inclined breaker zone, the large breaker teeth 30 serve to break down flie large wood chips and then to advance and distribute the stock in a uniform manner into the smaller teeth 34 of the intermediate zone. The dams 33 of the intermediate zone insure that the stock is uniformly subjected to the refining action of the parallel teeth of this 4 zone by preventing direct radial stock flow between the teeth.

On reaching the juncture 44 of the intermediate zone and the fine zone, the tendency of the partially refined stock to resist passage across the very fine teeth of the fine zone and to accumulate at the intersection of the zones is eliminated by the non-arcuate configuration of the juncture 44. Stock which might normally accumulate in this region is dispersed by the configuration of the intersection of the zones which tends to keep the stock moving uniformly into the fine zone. The effect may be likened to a saw tooth action since material in this region is subjected to a zone juncture of constantly varying diameter as the plates are rotated on the high speed refiner discs.

The stock in passing across the extremely fine teeth of the fine zone is reduced by the fine teeth in such a manner that the wood fibers are rolled along the tooth surfaces. effecting a rubbing of the fibers against one another and causing a fibrillation of the fibers to produce the desirable fiber condition shown in FIG. 7. It will be noted with reference to FIG. 7 that the wood fiber bundles 50 are effectively broken down into the individual wood fibers, forming what appears as feathery offshoots from the fiber bundles as shown particularly at 52, for example.

This pulp structure contrasts sharply with that shown in FIG. 8 which shows the same stock after refining with a conventional commercially available set of refining plates. Specifically, the fibers shown in FIG. 8 were produced on a refiner, one disc of which was equipped with Sprout, Waldron refining plates pattern D1B101 and the opposite disc of which was equipped with Sprout, Waldron refining plates pattern D1B109, the peripheral area or both discs being provided with Sprout, Waldron control rings pattern D4A127. It will be noted from the photomicrograph of FIG. 8 that the fiber bundles in the pulp refined with such conventional plates are not broken down or fibrillated into the feathery fiber condition achieved with the present plates as illustrated in FIG. 7. The fibrillated pulp produced by the present plates provides a stronger, more uniform pulp due to the very high degree of fiber separation. It should be noted that there are very few out or broken fibers in FIG. 7, the fibers for the most part extending from the main fiber bundles in a random arrangement.

As set forth above, it is believed to be the combination of the exceptionally fine teeth of the fine zone, the nonarcuate intersection of the fine zone and intermediate zone. and the slope of both the fine and intermediate zones which provides the high quality pulp such as shown in the photomicrograph of FIG. 7. Although each of these features is considered essential to the invention, certain variations in these features may be made without appreciably affecting the refining effect of the plates. For example, the intersection of the fine zone and the intermediate zone, although illustrated in the preferred embodiment as a succession of connected chords of equal length of an imaginary concentric circle, could be of many other non-arcuate configurations, the present form being chosen for convenience in manufacture. Similarly, although the inner ends 56 of the fine teeth 40 and the inner ends 58 of the intermediate teeth 34 are shown as beveled sharply inwardly, this is solely for convenience in the manufacture of the plates and the plates will function with equal effectiveness with the teeth continuing into abutting relation with the teeth of the interiorly adjacent zone.

The teeth of 'both the intermediate and fine zone sections 35 and 41 are arranged in substantially radial alignment in the illustrated embodiment although it has been found that changes in the angle of the teeth have no appreciable effect on the refining action of the plates. Although non-radial angling of the teeth of refiner plates is often employed to assist the flow of stock across the plate zones, no difiiculty in feeding the stock has been encountered with the plates of the present design and the illustrated substantially radial arrangement of the teeth of the various zones is preferred.

The size of the teeth of the fine zone 28 for the most effective refining action should be less than wide on 0100" maximum centers. This small size tooth has been found to function effectively to permit the steam developed in the refining operation to escape outwardly without interfering with the uniformity of stock flow across the attrition surfaces.

As an example of the slope angle of the intermediate and fine zones which has proven effective for a peripheral speed of the refining discs of 19,000 feet per minute, an inclination of .005 inch per inch of radius has been found to be satisfactory. For a slower peripheral speed, a greater slope would be desirable as indicated above. The slope of the breaker zone is of course substantially greater than the slope of the intermediate and fine zones and would also be dependent on the speed of rotation of the refining discs.

Although the refining plates illustrated show the several refining zones integrally cast in a single plate, the invention may be employed in an arrangement in which the fine zone for example may be a separable ring, particularly in view of the fact that wear occurs far more rapidly in the fine zone than in the other refining zones.

An alternate construction to the segmental plate array illustrated is a single annular refiner plate embodying the features of the present invention, a single plate being especially suitable for smaller size refiners.

In the illustrated embodiment, the attrition surfaces are toothed surfaces although it would be possible to employ other surface configurations such as hobs, grooves, etc. with a similarly improved result.

It has been found that by use of the present refiner plate, groundwood stock can be refined in one pass to achieve a sufliciently high pulp quality to make a second pass unnecessary. It is, however, anticipated that the present plates will usually be employed in two pass refining, especially where slow drainage pulp is desired,

Manifestly, changes in details of construction can be effected by those skilled in the art without departing from the spirit and the scope of the invention as defined in and limited solely by the appended claims.

We claim:

1. A refiner plate for use with a disc-type refiner for refining high consistency pulp comprising an attrition surface having a plurality of circumferentially continuous refining zones disposed between the inner and outer edges of the plate, the outermost refining zone having extremely fine, circumferentially continuous closely spaced attrition elements thereon, the intersection of said outermost zone with the adjacent refining zone having a configuration, said attrition elements in the outermost zone and the adjacent zone sloping inwardly of the plate, the inward slope of said zones and the continuous non-arcuate configuration of said intersection promoting the uniform feed of pulp across said outermost zone.

2. A refiner plate for use with a disc-type refiner for refining high consistency stock comprising a circumferentially continuous attrition surface adapted to receive a flow of stock passing thereacross from the inner to the outer edge thereof, a breaker zone on said attrition surface adjoining the inner edge thereof having relatively large attrition elements, an intermediate zone outwardly adjacent said breaker zone having smaller attrition elements than said breaker zone, and a fine zone between said intermediate zone and the outer edge of the attrition surface having extremely fine closely spaced attrition elements thereon, the intersection of said fine zone and said intermediate zone being continuous and nonarcuate in configuration and said attrition elements in the fine and intermediate zones sloping inwardly toward said breaker zone to promote the uniform feed of stock across said fine zone.

3. A refiner plate as claimed in claim 2 wherein the attrition elements of said fine zone comprise rows of extremely fine closely spaced parallel teeth.

4. A refiner plate as claimed in claim 3 wherein said teeth are less than wide on 0.100" maximum centers.

5. A refining plate as claimed in claim 2 wherein said fine zone intersects said intermediate zone along intersecting straight line boundries to provide a saw tooth feeding effect to advance the stock across the fine zone teeth during rotation of the plate in a refiner.

6. A refining plate as claimed in claim 2 wherein said breaker zone slopes inwardly at an angle greater than the slope of said fine and intermediate zones.

7. A segmental refiner plate for use in a disc-type refiner for the refining of high consistency stock comprising an attrition surface, said attrition surface including a plurality of circumferentially continuous refining zones adapted to receive a stock flow thereacross, the stock fiow passing across said attrition surface from the innermost to the outermost of said refining zones, the outermost zone comprising rows of circumferentially continuous extremely fine parallel teeth, the intersection of said outermost zone with the inwardly adjacent zone having a continuous non-arcuate configuration, the attrition surfaces of said outermost and inwardly adjacent zones sloping inwardly of the plate, the inward slope of said zones and the continuous non-arcuate configuration of said intersection promoting the uniform feed of stock across said outermost zone.

References Cited UNITED STATES PATENTS 1,556,323 10/1925 Garza 241-298 3,117,603 1/1964 Van Keuren 241-298 X 3,125,306 3/1964 Kollberg 241-298 3,141,272 7/1964- Horstman 241298 X 3,240,437 3/1966 Horstman 241-296 X FOREIGN PATENTS 430,729 5/1934 Great Britain.

RQBERT C. RIORDON, Primary Examiner D, G. KELLY, Assistant Examiner UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Patent No 3 ,473 ,745 A October 21 1969 Raymond E. Shook, Jr. et a1 It is certified that error appears in the above identified patent and that said Letters Patent are hereby corrected as shown below:

Column 2, line 2, "paralel" should read parallel line 32 "defining" should read refining Column 5 line 52, after "having a" insert continuous non-arcuate Signed and sealed this 16th day of June 1970.

(SEAL) Attest:

WILLIAM E. SCHUYLER, JR.

Edward M. Fletcher, Jr.

Commissioner of Patents Attesting Officer 

